/Engine/Plugins/Animation/MLDeformer/MLDeformerFramework/Source/MLDeformerFrameworkEditor/Public/MLDeformerGeomCacheSampler.h
Calculate the vertex deltas between the linear skinned mesh (skeletal mesh) and geometry cache. A delta cutoff length can be specified. Deltas with a length longer than this cutoff length will be ignored and set to zero. This can be useful in cases where for some reason due to some mesh errors some deltas are very long. Setting the DeltaCutoffLength to a very large value would essentially disable this filtering and always include all deltas. Typically a good value for the delta cutoff length seems to be 30.
void CalculateVertexDeltas ( const [TArray](API\Runtime\Core\Containers\TArray)< FVector3f > & SkinnedPositions, float DeltaCutoffLength, [TArray](API\Runtime\Core\Containers\TArray)< float > & OutVertexDeltas )